In the treatment of wounds, it is necessary for active substances which are intended or need to come into direct contact with the surface of the wound or the bottom of the wound to be administered by means of pharmaceutical forms which, by reason of their consistency, can be applied without gaps even to very uneven surfaces. This normally takes place with the aid of solutions, powders, dusting powders, sprays, semisolid preparations, such as ointments, creams and gels. The disadvantages of these pharmaceutical forms become clear, in particular, when it is necessary to give doses of highly active substances in a small amount, accurately and reproducibly, or when controlled release from the pharmaceutical form is desirable for the therapy to maintain a uniform concentration of active substance in the wound throughout a particular period.
Wound dressings which, by reason of their composition and their structure, are loaded with active substances and release the latter in a delayed or controlled manner are described, for example, in U.S. Pat. No. 5,098,417, in EP 49 177 or in DE-B 11 90 608. These wound dressings have the disadvantage that, especially in the case of deep wounds, they do not come into contact with the bottom of the wound. The ability of such wound dressings to function is, moreover, greatly dependent on the interaction with wound fluid, since, the release can take place only by diffusion of the active substance at the interface between wound dressing and wound fluid or by erosion of the active substance from the wound dressing after uptake of fluid and swelling of the carrier material. Since the fluid conditions in wounds vary greatly between individuals and depending on the type of wound and phase of wound healing, it is not possible to achieve comparable and reproducible kinetics of release with such wound dressings in vivo.